A sonobuoy is a device utilized for the detection of submerged targets in the water environment. Typically, a sonobuoy is launched from a relatively slow flying aircraft, and after launch a parachute is deployed to slow the sonobuoy descent. Upon entering the water, the parachute is decoupled and a surface flotation unit is activated. This surface floatation unit generally contains transmitter/receiver equipment, along with an antenna.
Tethered to this surface flotation unit, and extending vertically in the water column below the surface flotation unit, is a transducer array utilized to detect acoustic signals from a potential target. In a passive system, these acoustic signals may emanate from a target to be detected and are received by a transducer array. Alternatively, the sonobuoy apparatus may include an active acoustic projector, in which case the transducer array detects the acoustic signals reflected from the target. These detected signals are provided to the transmitter at the floatation unit which, upon command, transmits them to a remote location, such as the deploying aircraft.
A common type of sonobuoy in use is an active xe2x80x9cAxe2x80x9d size sonobuoy which is packaged in a cylindrical container having a length of around 3 feet and a diameter of around 5 inches. Basically, in acoustic systems, the larger the receive array, the greater will be the sensitivity of the system. However, a large receive array is incompatible with a relatively small sonobuoy container. To achieve the sensitivity of a large receive array, many small sonobuoys, or larger sized containers must be utilized. The present invention provides a solution to this incompatibility problem.
Sonobuoy apparatus in accordance with the present invention includes a weighted canister for insertion into a water environment to detect potential targets. Packaged within the canister is a surface unit containing transmitter/receiver equipment for communication with a remote location, such as the launching aircraft or vessel. The canister also includes a support unit, which may be constituted by a housing for receive transducer electronics. A plurality of arms is provided, each arm including a plurality of nested telescopic arm sections, with a first of said arm sections being connected to the support unit in a manner such that the arm is capable of limited upward rotation after the canister pulls free and falls away. A weight member, which may be an acoustic projector if the sonobuoy is an active sonobuoy, bears against the lower portion of each arm section and causes extension of the nested arm sections, as the sonobuoy falls through the water column, and before the canister pulls away and falls free. After the canister pulls away and falls free, an arm deployment arrangement deploys the extended arms to a desired orientation, such as horizontal. The deployed arms carry receiver transducers for the detection of target signals.